Underreamer



June 28, 193.8. Y Hl c;L SMITH 2,121,888

UNDERREAMER Filed oct. 14, 1935 2 Sheets-Sheet 1 'z5 l 2 66 1 I g 25 /a 26 2@ l 2g, ;1z,i-:.\\\\

June 28, 1938.l

Filed 0G11. 14, A1955 H. c. SMITH y 2,121,888

UNDERR'EAMER 2 Sheets-Sheet 2 ATTORNEY fis Patented June 28, y1938y UNITED STATES ENT OFFICE l 2,121,888, Y UNDERREAMER y Herman' o. smitmwhittir, Calif.

Application. vkoctober 14, i535, serial Nefiaeos claims. (crass-7e.)

This inventionnrelatesto underreamers of the rotary type. As is well known in the art, underreamersV are used to enlarge a well hole when the drilling tool: has, for one reason or another,

' `5; failed to maintain a proper clearance.

hole `must be carefully reamedin order that' they will' not interfere with the passage of metal casing. lIn addition to the above use of underintroduced into the well hole for the purpose of enlarging thewell, hole vat points where free space about the casing is desired for the purpose of `introducing cement in excluding of Water.

`The. present invention is thoughtv to be novel in that it is provided with means adapted to enlarge a hole to a certain diameter, which said means likewise actsvtosteady the tool and to guide its forward movement, together with further cutters adapted torream the hole to size to receive casing.

An object ofthe invention is the provision Another object is the provision in an under-- reamer of. novel cutting means so constructed and arranged as to relieve thrust from the cutter bearing elements liny the underreamer.

Another object is the 'provision of an underreamer incorporating the novel construction which, during aA reaming action, relieves the kelly.y of back thrust. v

\ Another object is the provision in an underreamer of novel'means for cutting formation which does not track but at all times chips and shears the formation and whether it be hard or soft.

Another object is the provision in a device of the character stated of reaming cutters which may be projected into formation engagement or retracted therefrom by positive, eii'cient and fool-proof means.

view, as will hereinafter appear as the specification proceeds, the inventionl includes novel cornbinations of parts, members and features all as illustrated by way of' example in the specificationand drawings.

In the drawings:

AFigure 1 isa fragmentary elevation, partly in section, ofza wellfhole having casing in part received therein withnthe` improved' underreamer showniinfposition to', underream the hole,

reamers just indicated, underreamers mayv be With the objects above named and others in4 Figure 2 is a view partly in fragment and in vertical section onfan enlarged scale of the improved underreamer, the parts thereof being shown in one position, v

Figure '3 is a fragmentary vertical sectional view of the underreamer shownA in Figure 2, certain parts thereof being in changed position from that of Figure 2,

- Figure .1i is a cross sectional View on the line ll-ai of Figure 3,and, Figures, 6 and 7. are sectional yviews taken on the'lnes 5--5, 6--6 .and 1-1 of Figure, 2.y

Referringv now to the drawings, the underreamer as an entirety is designated by the numeral'l and the same includes a body i2. body 2lis provided at one end with a pin 3 and the opposite end' with a box 4. As is customary in' rotary. underreamers, the body is provided 'with an axial bore 5 extending between the pin andthe box functioning as a water course. The underrearner body is adapted Ato be secured to a dr-illstring 6 through the medium `of a suitable 'collar 1- secured to the pinlor vin any other suitable manner'. The box in turn` generally receives some type of bit 8 which, in' the present instance, is shown in Figure 'l as being a fishy tail 4andi said sh-tail bit is provided with Water` coursesA 9 wherebyV uid passed ythrough the drill 'string may inturn be passed through the Water course 5 and out the courses 9 for the purpose of washing away the cut formation. This fishtail acts as a means Afor cutting the formation to a given size and also guides the underreamer inits movement in the forming of the hole.

Thev underreamer body in the present instance is provided with three equidistantly spaced underreamer cutters, as shown in Figure 6 at I3, Mand. l5, the cutters being designated as entireties by the numeral I6. The precise form of cutter shown in the drawings forms the basis for my co-pending application led contemporane-V The ously lwith the filing of this application on October 14, 1935,.Serial No. 44,907. Y,

As vthree underreamer cutters are used in thev present instance, and as the cooperating structure for carrying each cutter toallow it to be brought into formation engagement or out of formation engagement is identical, only one of said cutters with its associated' devices will be described, the same'reference characters applying to the' others. Also, it is to be understood that any number of underreaming cutters may be provided other than the three as shown, the drawings being illustrative only, of a possible embodiment of the invention. j

Figures 2 and 3 show the general structure for one of the underreaming cutters and its actuating device. Briefly, the body 2 is provided with three recesses or channels of extended length and depth. An elongated eccentric recess for the cutter assembly, shown at I3, is shown at I1. Within the recess and adjacent the pin end thereof is a block I8 provided with steps I9 outwardly facing from said recess. These steps have risers at 26 at an angle other than 90 degrees to the longitudinal axis of the underreamer body. The steps are in descending relation from that portion of the said block i8 adjacent the pin end to the lowermost portion which is in the direction of the box end of the body. This block may be held to the body in any approved manner, such as by welding, brazing or the like, as indicated at 2l. Adapted to cooperate with the block I8 is a block 22 functioning as the cutter actuator medium as hereinafter described. This block is provided on one face with steps 23 complementary to the steps of the block I6. The outermost face 24 of the block 22 is plane and substantially parallel to the axis of the body 2.

The block 22 is provided with transverse slots 25 and 26. The slots 25 and 26 are elongated, as shown in Figure 1.

'I'he block I3 is provided with a threaded bore 21 and a screw-threaded bolt 28 is threaded to the threads of the bore 2 with thek head 28 of said bolt received within the slot 26 (seeFigure l) it will be seen that the construction is such that whereas the block I8 is held against movement, the block 22 may, in certain instances, move relative to the block I8, to-wit, downwardly viewing Figure 2 and that the said bolt, as tted within said slots allows such movement to occur to a limited degree. When this block 22 moves downwardly relative to the block I8, it is evident that the steps of one block slide over the steps of the other. f

The block 22 is provided with a bore or socket 2s projected at an angle inwardly-from one end 35 thereof. in this connection, it is to be observed that all portions of the bore do not lie in the same longitudinal axis and that the bores are in offset' relationship, to-wit, that portion of the bore at 3l lies on a different axis from the portion of the bore shown at 32, which results in the formation of annular steps or shoulders 33 and 34. The opposite bounding end wall 35 of the recess il is inclined downwardly in part at 36, and then provided withra semi-circular wall 31. The sides bounding the semi-circular Wall are substantially parallel as shown in Figure 7 at 33 and 39.

The underreamer cutter includes a shank 46 formed with a central bore 4I through which bore is passed a pin 42, the end portions of which pin extend beyond ends of the shank of the cutter. The periphery of the shank is provided with cutter teeth, designated generally as 43 and segregated into sones 44, 45, 46 and 41. The number of zones of cutter teeth may vary. All of the cutter teeth are in the form of threads which may be milled or otherwise constructed, and the threads of alternate Zones may be right and left, respectively. The` zone shown at 44 has helical right threads; that at 45 helical threads, and so on for the remaining zones, each zone alternating as to the direction of the threads. In `addition thereto the threads may vary as to pitch diameters, the pitch diameters of the threaded zones at 44 and 45 varying, the zone 45 being greater, whereas the threaded zones at 46 and 41 may have the same pitch diameters although the pitch cutter.

diameters may be greater than the zone 45. It has been found in actual use and practice that a cutter of the character just described does not track, which is to say, follow the same groove when the underreamer is in operation and being rotated, but tends to constantly chip and break olf new formation, which is one of the factors 1n producing what I term a balanced underreamer.

The underreamer cutter is assembled in such a manner that one zone thereof rocks relative to the underreamer body while a second zone moves substantially radially opposite said body to bring the teeth of the cutter into formation engagement. This is accomplished by providing mounts 48 and 49. The lowermost mount has a curved end wall adapted to be socketed within the semi-circular recess 31 of the body 2 and formed with a circular socket 5I adapted to receive one end of the pin 42. The construction is such that roller bearings 52 may be interposed between the wall bounding the circular socket and the periphery of the pin.

The mount 43 includes a portion 53 provided with a circular socket 54 receiving the opposite end of the pin and between the wall bounding the socket 54 and the periphery of the pin are roller bearings 55. This portion of the mount 48 has the periphery thereof so formed as to `best t within the recess il (see Figure 6) wherein it will be seen that the portion 53 is provided with two parallel side walls tting closely between the side walls of the recess. This close-fitting construction is true for the lowermost mount 49, as see Figure 7. Thus, side play between the mounts is effectively prevented and hence the cutter is held rigidly either within or partially out of the recess E'I.

The mount 48 is provided with an arm eX- tension 56, the extension having substantially parallel side walls 57 and 58, and the front face of the arm is inclined or at an angular relationship at 59 relative to a portion 69. The crosssectional width of the arm at the Zone of the inclined face is greater than the cross-sectional width of the arm at the Zone 65 and this construction providesl a shoulder at 6I or what may be termed the rear portion of the arm. For convenience of description, it may be said that the socketed base of the mount is provided with an arm having an offset head, which head is formed with an end socket 62. This socket faces inwardly of the socket or bore ofthe block 22, and interposed between the last named sockets is a coil spring 63. This coil spring normally urges the mount 48 outwardly of the bore 3l, or from the position shown in Figure 3, to the position shown in Figure 2.

Reference to the figures shows that that portion of the recess' I'i' which houses the blocks I8 and i9 has a reduced width from that portion which houses the cutter. This construction will depend largely upon the size of the cutter used, and this reduced construction of the said recess likewise occurs at the socket mount for the said The operation, uses and advantages of the invention are as. follows:

If it is desired to underream a hole beneath casing, for instance, the casing shown at I2 in Figure l, a semi-circular ring of the form illustrated in Figures 3 and 4 at 54 may be employed for holding the cutters within the recesses I1. Referring to Figure 3, it will be seen that this ring is provided with an internal shoulder 65 bearing upon a portion of the body and having a part engaging the block 22 to hold the block in a definite position relative to its cooperating block I8. More particularly, the block has been moved from the position shown in Figure 2 to that of Figure 3, thel steps of the block 22 having slid downwardly over the steps of the block I8 and in so doing, rocked the cutter inwardly of the recess Il. This rocking action is effected by the socket arrangement for one end of the body and the said cutter, kand for the opposite end by causing the arm with its socketed head to move upwardly within the bore 3l of the block 22 to compress the spring 63. In moving the cutter inwardly of the recess, it will be observed that the inclined surface 59 of the mount 48 slides along the inclined wall bounding the socket 29 until such time as the head end of the arm strikes the inclined shoulder 34 to swing the head inwardly, at which time the lshoulder 6I and. the parts thereof will then assume the position shown in Figure 3. When this position is reached, the cutter blades all have the edges thereof spaced inwardly of the casingso that said blades do not engage the casing. This semi-circular ring 64 holds the parts in the position shown in Figure 3, as the underreamer is lowered within the casing, the said semi-circular ring64 will be forced from engagement with the block 22 as the underreamer is lowered by the lowermost rim of said semi-circular ring 64 engaging the topof the casing, as illustrated. When the semi-circular ring is removed from its holding engagement with the block 22, the coil spring 63 tends to move th'e block 22 upwardly relative to the block I8 and in so doing to cause the cutter to rock outwardly of the recess Il. Thus, the

rparts may assume the position shown by dotted lines in Figure 3 at 66. However, the block 22 in moving upwardly engages the inner surface of the casing and holds the cutter edges spaced from the inner surface of the casing, as illustrated by the dotted lines at 61. In passing through the casing, the cutter blades thereafter do not contact the inner surface of the casing or the couplings, with the result that the cutter blades will not be damaged. After the cutter blades have emerged below'the casing, the block 22 will still hold the cutter blades out of formation engagement until such time as the uppermost end of the block is out of engagement with the casing, whereupon the coil spring 63 will move the block from the dotted line position of Figure 3` to the full line position of Figure 2. At this time, the underreaming operation may occur in the manner illustrated in Figure 1. In this underreaming operation, the fish-tail bit 8 is making holle, while the underreamer cutters are forming it to size. These cutters chip the formation, whether it be hard or soft, and as stated, do not track the formation but constantly work upon new formation. This lack of tracking relieves the bearings fromend thrust, and is a distinct advantage in drilling as it relieves the kelly and provides what may be termed Aa balanced underreamer. When the underreamer is in operation, the teeth at the vZones 44 and 45 will cut the formation to proper size whereas the teeth at the Zones 46 and 41 will gradually taper the formation, with the result that the underreamer progressively acts upon the formation to produce the diameter of cut desired.

Each block 22 isprovided with a shoulder 68 inclined downwardly relative tothe longitudinal axis of the underreamer body, and in such position as to readily engage the lower end of casing when it is desired to withdraw the underreamer as an entirety from the well hole. When the lowermost end of the said casing strikes the inclined shoulder 68 of each block 22, the block will be pushed downwardly relative to the block I8. The steps of the blocks 22 sliding over the steps of the blocks I will rock the cutters and the mounts therefor inwardly of each recess l1 in the body. Thus, the cutters will be out of casing engagement while the said underreamer is being withdrawn through the casing.

I claim:

1. The combination in an underreamer, of a body formed with an elongated recess, the wall bounding one end of said recess being in the form of a curved socket and the side Walls bounding the recess being parallel, a mount fitted within said curved socket and adapted to rock transversely without side movement therein, a pair of relatively movable stepped blocks within said recess, a second mount movable relative to one of said stepped blocks, and a reamer cutter interposed between said two mounts, and means normally urging one stepped block relative to one of Asaid mounts to in turn rock the reamer cutter in one direction.

2. The combination in an underreamer, of a body provided with an outwardly facing stepped zone, a block provided with steps adapted to cooperate with the stepped zone of the underreamer body, said block being formed with a bore, an underreamer cutter, means for rockably mounting one end of said underreamer cutter to said body. and mounting means at the opposite end of said underreamer cutter in part received within the bore of said block, movement of said block rocking the underreamer cutter relative to the body.

3. 'Ihe combination in an underreamer for oil wells, of a body formed with an elongated recess, an underreamer cutter within said recess, a mount rockably secured to said body for holding one end of said reamer cutter, a mount for the opposite end of said reamer cutter, and an adjustable slide movable relative to the last named mount to rock the reamer cutter inwardly of or outwardly from said recess. f

, 4. In an underreamer, a body formed with an elongated recess, a block fitted in the upper end of said recess and formed with an outer stepped face, a second block tted in said recess and formed with an inner stepped face slidably tted to the stepped face of said first block, for enabling said second block to be moved inwardly or outwardly with relation to said first block and said body, an underreamer cutter, means for rockably mounting one end of said underreamer cutter in said body, and means for mounting the other end of said underreamer cutter in said second block whereby said underreamer cutter is rocked inwardly or` outwardly with relation to said bodyas said second block is moved inwardly or outv wardly as aforesaid. y 5. In an underreamer as claimed in claim 4, in

which the second block is provided with a slot,

and a screw bolt is extended through said slot and seated` in said first block for holding said second block in operativev relation to rsaid rst ,l 

